FIG. 2A shows a typical trunked radio communication system block diagram 200. Resource controller 203, for example Motorola Smartnet II model number `T5184`, is coupled to a database 201 and is used to allocate communication resources within the system. Resources, including those used for both communication and control, are shown in the form of repeaters 205, 207, 209 and 211. These repeaters, under the direction of the resource controller 203, transmit and receive radio frequency signals to and from communication units 213, 215, for example Motorola Saber portable model series H99QX and Maxtrac mobile model series D35MWA. One of these repeaters, for example repeater 205, may be a dedicated control resource; that is, repeater 205 may be solely used to transmit and receive a predetermined set of communication control signals. This predetermined set of signals are generally sent via a control channel 221 to communication units 213 and 215. In such a system the remaining repeaters 207, 209 and 211 are used as voice/data repeaters which define a set of communication resources, for example, voice channels 223.
The sending of sub-audible signal data to communication units within such a system is known. In today's systems, control data (i.e. data which serves to direct inbound and outbound communication between communication units) is sent via a control resource, or channel. This control data generally includes a fixed identification code (ID) for the requesting communication unit. This code may include fleet information, sub-fleet information, and other parameters directly associated with the communication unit. In one type of system this control data may be transmitted sub-audibly on the same channel as the ensuing voice transmission. In another type of system, this control data may be transmitted on a resource, or channel, separate from the voice channel assigned, and may be dedicated for this purpose.
Currently, the fixed ID cannot be effectively used by the operators of receiving communication units to quickly identify the operator of a transmitting communication unit. This ID is generally not useful to an operator since it has no meaningful relationship to the transmitting operator. Even if a communication unit, or radio, is permanently assigned to an operator, the operator's name is not typically related in any way to the fixed ID of that radio. Worse yet is the case where an operator obtains a different radio daily.
In addition to the aforementioned dilemma, there is another problem with the current systems. The transmission of a communication unit's fixed ID to a receiving, or target, radio is used primarily to direct the other radios in the same fleet, or group, to tune in to the correct voice channel frequency for further communications. Once in this receiving mode, however, a communication unit is unable to monitor control data without potentially missing voice data.
As in any real time system, execution speed and timing are critical elements to the successful operation of that system. Today's trunked radio communication systems are no exception to this general rule. Access time to a voice call, though, is directly related to the amount of congestion currently existing on the control channel granting access to that call. Required information, including for example fleet and sub-fleet information, defines the lower boundaries for this critical access time. Obviously, sending additional information, for example the name of the operator transmitting a particular voice call, on a control channel, or resource, presents the problem of lengthening this critical access time, adding to an already over-burdened control resource.
Accordingly, there exists a dire need for a trunked radio communication system having the capability of sending operator-specific information to all receiving communication units for a particular call. Consideration must be made for minimizing increased access times, flexibility of the information to be sent, and efficiency with respect to a new radio joining an established call and still getting the information.